In case you ever wondered what all them there maths were...
This first chart shows how many hits you need to land in order to actually wound a target.

This second chart shows how much more effective (potent) your attacks are compared to how much you spend on the skill.

For instance, hitting for 3 damage against someone with 3 body takes just as many swings as someone hitting for 2 damage.
Therefore they have equal effective ratings for the purpose of defining "potency" compared to the starting damage value of 1.
(The green boxes represent the point at which you've maximized your damage-to-cost ratio in a particular category)* = hypothetical/predicted numbers used as estimates for calculations
** = estimates based on a starting character build + skill points to achieve that ability.
(Obviously this doesn't apply to Pierce and Slay, so take these calculations with a grain of salt)
Relational Gain = How many categories improve when purchasing this skill in relation to the last.
Average Increase = The total average % gain towards hit effectiveness in relation to the skill before it.
Optimal Rating = The number of categories where damage output is maximized without 'overkill'.
Est. Skill Cost = Just what it says. Mirrored from Melee Damage skills.
("0 to 4" reflects option to purchase martial or great weapons.)Effective Gain = Relational gain divided by how many more skill points it takes to reach this damage level.
Effective Average = Average Increase divided by how many more skills points it takes to reach this damage level.
Some things to take away from this: - The increase of effectiveness from 3 Pierce to 4 Pierce damage is almost negligible. The only time 4 Pierce would make a difference is vs. someone with exactly 3 body, ignoring armor, (or a monster with > 5 body)
- If, theoretically, someone were to break cap and swing for 5 damage, the effective damage output would be surprisingly low.